The invention relates generally to the brazing of articles containing aluminum.
The German Auslegeschrift No. 1,962,760 discloses a brazing alloy consisting of 4 to 20 percent by weight of silicon and 0.01 to 10 percent by weight, preferably 0.05 to 2 percent by weight, of the elements of the group composed of bismuth, strontium, barium and antimony with the remainder consisting of aluminum and impurities due to the production of the alloy. This publication teaches the use of the brazing alloy as a filler metal for the fluxless brazing of aluminum-containing articles in a non-oxidizing atmosphere or in a low vacuum.
The German Offenlegungsschrift No. 2,143,965.6 also discloses a brazing alloy for the fluxless brazing of aluminum-containing articles which likewise consists of 4 to 20 percent by weight of silicon and 0.01 to 10 percent by weight, preferably 0.05 to 2 percent by weight, of the elements of the group composed of bismuth, strontium, barium and antimony with the remainder consisting essentially of aluminum and impurities due to the production of the alloy. The characteristic of this alloy resides in the fact that, instead of or together with the bismuth, strontium, barium and antimony, it contains beryllium in amounts of 0.00001 to 1.0 percent by weight and, preferably, in amounts of 0.0002 to 0.1 percent by weight.
The foregoing brazing alloys have been found to yield good results in practice. However, they possess the disadvantage that they impose relatively stringent requirements as regards the presence of a non-oxidizing atmosphere or a low vacuum during the brazing operation.